In the complex `[Co(NH_3) Cl]Cl_2` The primary & secondary valency of central metal respectively are.

Options

A. 2 and 8
B. 3 and 5
C. 3 and 6
D. 2 and 6

Answer

To determine the primary and secondary valency of the central metal in the complex [Co(NH₃)Cl]Cl₂, we will follow these steps:

### Step 1: Identify the central metal and its ligands
The central metal in the complex is cobalt (Co). The ligands attached to cobalt are ammonia (NH₃) and chloride (Cl⁻).

### Step 2: Determine the oxidation state of the central metal (Primary Valency)
The primary valency corresponds to the oxidation state of the central metal.

- Let the oxidation state of cobalt be \( x \).
- Ammonia (NH₃) is a neutral ligand, contributing 0 to the oxidation state.
- Chloride (Cl⁻) is a negatively charged ligand with a contribution of -1.

The complex has two chloride ions outside the coordination sphere, which are counter ions. Therefore, we can set up the equation:

\[ x + (0 \times 5) + (-1 \times 1) + (-1 \times 2) = 0 \]

This simplifies to:

\[ x - 1 - 2 = 0 \]

Thus,

\[ x - 3 = 0 \implies x = +3 \]

So, the primary valency (oxidation state) of cobalt is +3.

### Step 3: Determine the coordination number (Secondary Valency)
The secondary valency corresponds to the coordination number, which is the total number of ligands directly bonded to the central metal.

- There are 5 ammonia ligands (NH₃).
- There is 1 chloride ligand (Cl⁻) directly bonded to cobalt.

Adding these gives:

\[ 5 + 1 = 6 \]

Thus, the secondary valency (coordination number) of cobalt is 6.

### Conclusion
The primary valency of the central metal (cobalt) is +3, and the secondary valency is 6.

**Final Answer:**
Primary valency = 3, Secondary valency = 6.

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